Solvent refining of hydrocarbon oil



May 7, 1935- l R. E. MANLEY v 2,000,707

SOLVENT REFINING OF HYDROCARBON OIL Filed Jgn. 31, 1933 J .55772//1/6 wins? :H4/m35@ B Y I' /7/5 A TTU/e/VEY Patented Mey 7, 1935 UNITED STATES PATENT OFFICE 2,000,101 soLvENT nn'rnvnvgnor maooABnoN Robert E. Manley, Beacon. N. Y., signor to The Texas Company, New York, N. Y., a corporation of Delaware This invention relates to refining hydrocarbon oils by solvent extraction .and to an improved process for carrying out the extraction.

The inventioncontemplates a continuous countercurrent process for extracting hydrocarbon oils, such as lubricating oils, kerosenes, naphtha fractions and the like, with a selective solvent liquid such as furfural, or a derivative thereof, for the removal of undesired constituents wherein the solvent is continuously recovered `from the separated hydrocarbon fractions and recycled through the system for treating fresh oil.

, ThisV application is a continuation-impart of my copending application Serial No. 597,141, led March 7, 1932, for Solvent refining of hydrocarbon oil.

More specifically, my`invention comprises continuously and countercurrently -contacting hydro.- carbon oil, such as a llubricating oil fraction, with furfural or a related compound selected from the furan group of heterocyclic hydrocarbons, form-l ing a liquid portion comprising the desired fractionl of the eiland some dissolved solvent liquid, and another liquid portion comprising the major part of the solvent liquid together with dissolved hydrocarbons of undesired characteristics. The resulting liquid portions are separately. treated with water which is miscible with the furfural under the influence of heat and thus adapted to displacethe dissolved oil therefrom. r The displaced oil constituents may then be withdrawn and the remaining mixture of furfural and water subjected to cooling in order to separate the water and recover the furfural fortreating fresh oil.

The treatment of the solution of furfural and dissolved oil constituents with water comprises mixing about one or more parts by volume of water with one part of vsolution and heating the resulting admixture under pressure sulcient to prevent substantial vaporization of the water to temperatures which may range from about 200 F. to about 325 F. or higher, depending upon the nature ofthe oil constituents to be displaced and also the proportion of water added. The heating is carried out under suitable conditions of temperature and pressure to eect miscibility between the water and furfural whereby the oil constituents are displaced from solution in the furfural, The resulting mixture is then subjected to settling while hot and while still under pressure sulllcient to prevent substantial vaporization of the water, so as to effect separation'of the displaced oil constituents fromthe fui-rural. The displaced oil is then removed by decantation.

The remaining mixture of furfural and water is then cooled to a temperature at which the water separates from the furfural, following which it may be removed by decantation, leaving a substantially water and oil-free furfural solvent ready for use in treating further oil.

The methodvof my invention is not restricted to the recovery of furfural from oil but is also adapted to the recovery of related compounds of the furan group of heterocyclic hydrocarbons, such as furfuryl alcohol, furfuralcohol, tetrahydrofurfuryl alcohol and the like. 'Ihese solvents,A like furfural, exert a selective solvent action upon the mineral oils as between the -naphthenic and parainic constituents of the oil and are, therefore, adaptable to the solvent rening of mineral oils. 'Ihese solvents may, therefore, after the solvent treatment of mineral oil,

be advantageously recovered by the method of my 2o `Gravity'A. P. I 19.1

Percent carbonresidue .26 PercentV sulphur .32 Saybolt universal viscosity:

At F 645 At 210 F 57 Viscosity index 10 This oil is withdrawn from a storage tank l and is passed through a heater 2 wherein it may be heated to a temperature of from about F. to about 200 F. The heated oil is then introduced to a mixing chamber 3 wherein it is' brought Y into intimate contact with furfural partially saturated with material extracted during previous contact with oil during a subsequent stage of the treating process. 'Ihe proportion of solvent to oil may, for the purpose of this example, be about one part of oil to one part of furfural. The resulting mixture of oil and furfural, including extracted material dissolved in the furfural, is continuously withdrawn from a central portion of the mixing chamber 3 and conducted to the middle portion of a settling chamber 4 advantageously of substantially greater volume thanV that of the mixing chamber 3, and wherein stratification occurs. Thus, at all times within the settling chamber 4, there exist three strata; the middle stratum comprising separating liquids, the upper stratum consisting of separated oil of relatively high viscosity index and a small amount of solvent dissolved in the oil, and the bottom stratum consisting of extracted bodies including those of relatively low viscosity index dissolved in a relatively large amount of solvent. I

The upper stratum or layer is continuously decanted and conducted to the bottom of a succeeding mixing chamber 5. Fresh furfural is introduced to the upper portion of this mixing chamber wherein it is brought into intimate contact with partially-treated oil being received from the settling chamber 4.

The mixture of oil and furfural is continuously Withdrawn from the middle .portion of the mixing chamber 5 and conducted to the middle portion of the settling chamber 6 wherein stratification occurs in a manner similar to that in the settling chamber 4. The separated oil and associated solvent is withdrawn from the upper portion of this settling chamber for recovery therefrom of the solvent, while the bottom layer comprising the bulk of the solvent together with dissolved matter, is conducted to the bottom of the mixing chamber 3 wherein it is mixed with fresh oil entering the system as already described. The furfural, substantially completely saturated with extracted material, is withdrawn from the bottom of the -settling chamber 4 and subjected to further treatment for the recovery of the solvent, in a manner similar to that of the treated oil portion 1 mentioned above and which will now be described in detail.

The treated oil containing a small amount of dissolved furfural, as removed from the top of the settling chamber 6, is conducted to a heater 1 wherein it is admixed with water and heated, under a pressure of about thirty or forty pounds, to a temperature of around 275 F. and then introduced to a settling chamber 8.

At temperatures around 200 F. water becomes fairly miscible with furfural and becomes substantially completely miscible therewith at about 275 F. so that the oil is displaced from the solution. In some instances, it may be desirable to employ temperatures of around 325 F., in which case the proportion of water required may be considerably reduced. This separation occurs ink the settling chamber 8, the displaced oil accumulating as an upper layer, while the mixture of furfur'al and water collects in the bottom of the settling chamber. The separated oil is then withdrawn from the top of the settling chamber 8 into a receiver 9, and may contain small amounts of solvent which can be removed by distillation or during subsequent treating.

The hot mixture of furfural and water collecting in the bottom of the settling chamber 8 is continuously withdrawn and conducted through a cooler I0 wherein it is cooled to a temperature of around F., at which temperature water is no longer `miscible with the furfural. The cooled mixture is then introduced to a final settling chamber I I to effect complete separation between the water and the furfural. The water is with-'- drawn from the upper portion of the settling chamber I I and returned to the inlet of the heater 'I, wherein it is admixed with a fresh incoming stream of treated oil and furfural.

In a similar manner the solution of extracted l matter and furfural is conducted to a heater I2 wherein it is admixed with water and heated to a temperature of around 275 F., following which it'is introduced to a settling chamber I3. From this separating vessel, the extracted material separated fromthe solvent by the water is withdrawn from the upper portion of the vessel to a receiver I4. The hot mixture of furfur'al and water is Withdrawn from the bottom of the chamber I3 through a cooler I5 to' a i'lnal settling chamber I6. The water separated from the furfural in this chamber is withdrawn there-l it is desirable to employ a closed system to per- Y mit carrying on the process under suiilcient pressure to prevent vaporization of any of the liquids or materials entering into the process.

The solvent treated or separated oil collecting in the receiver 9 and the extract collecting in the receiver I4 will each have the following'tests:

Spgted Extract Gravity A. P. I 22. l l2. 8 Percent carbon residue. l 14 .98 Percent sulphur 17 37 Ssybolt universal viscosity:

A F 471 1285 64 63 Viscosity index 39 below 0 The temperature and pressure conditions prevailing in the solvent recovery step may be varied. For example, when recovering furfural from relatively viscous oils, it may be of advantage to heat the mixture of water with oil and furfural solution to a temperature of around 300 F. or 325 F. and under a pressure of around 75 or 100 pounds gauge, in order to effect displacement of the oil constituents from the furfural. Employment of higher temperatures is also of advantage as regards the amount of water required for mixing with the solution. At temperatures of around 300 or 325 F. suitable proportions may comprise about one part of water to one part of oil-furfural solution. At lower temperatures, a correspondingly larger proportion of water is required, as, for example, at temperatures of around 200 F., it may be desirable to use about 10 or 15 parts of water to one part of solution. y

While the treatment of lubricating oilfractions derived from an asphalt-base source has been described in the foregoing example, the invention is not restricted to the treatment of this type and is equally well adapted to treating paraffinbase type' oils as well as various mineral oil fractions.

The method ofmy invention is particularly well adapted to the refining of naphtha or kerosene fractions with furfural, and from which treated fractions the furfural may be recovered by water displacement as above described.

Also the invention is not limited to any particular set of operating conditions since the temperatures, or the proportion of solvent to oil undergoing treatment, may be varied at will, depending on the characteristics of the desired nal product.

Obviously many modications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The method of recovering furfural from mixtures of furfural with hydrocarbon oils which comprises heating the furfural and oil in admixture with water to a temperature of from about 275 F. to about 325 F., effecting separation of the oil constituents from the Iurfural while maintaining the mixture at substantially such temperature, removing the separated oil, and cooling lthe remaining mixture to separate and recover the furfural.

2. The method of recovering furfural from mixtures of furfural with mineral lubricating oil which comprises heating the Iurfural and oil in admixture with waten to a temperature of about 325 F., maintaining the mixture in a quiescent condition while still hot to eiect separation of the oil from the mixture, removing the separated oil, cooling the remaining mixture to about F. to separate the water from the furfural, and

removing the separated water leaving the iurfural substantially free from oil and water.

3. The method of recovering Iurfural from mixtures of furfural with hydrocarbon oil which comprises mixing the furfural and oil solution with at least an equal proportion of water, heating the resulting admixture under pressure to a temperaturefo from about 275 F. to about 325 F.7 subjecting the resulting mixture, while hot, to settling in a relatively quiescent condition and under suillcient pressure to prevent substantial vaporization of water whereby the oil is separated from the furfu'ral, removing the separated oil, and cooling the remaining mixture to separate and recover the Iurfural.

4. The continuous method of recovering furi'ural and the like from a' solution of oil and furfural and the like, comprising mixing the solution with a substantial proportion of waterpass ing the resulting admixture in a conned stream through a continuous tubular heating zone wherein it is subjected to intimate mixing and heating under superatmospheric pressure at a temperature of about 300 F. whereby the water and furfural become miscible, subjecting the mixture, while hot, to settling under pressures sufficient to prevent substantial vaporizaton of the water whereby the oil is separated from the mixture, removing the separated oil, and cooling the remaining mixture to effect separation of the furfural from the water.

'ROBERT E. MIANLllY.- 

